Association Between Ultrasonographic Evidence of Nerve Entrapment and Pain Outcomes After Nerve Decompression in Painful Diabetic Peripheral Neuropathy

Objective: To evaluate whether preoperative ultrasonographic evidence of nerve entrapment is associated with pain relief after lower-limb peripheral nerve decompression in patients with painful diabetic peripheral neuropathy (PDPN). Methods: This single-center retrospective cohort study included 110 consecutive patients with PDPN who underwent bilateral lower-limb peripheral nerve decompression between February 2023 and June 2024. After three patients were lost to follow-up, 107 were analyzed. Preoperative ultrasonography assessed the bilateral common peroneal and tibial nerves. Patients were classified as ultrasound-positive if at least one examined nerve met the specified focal entrapment criteria and as ultrasound-negative otherwise. Numeric rating scale (NRS) scores were recorded preoperatively and at 7 days, 6 months, and 12 months after surgery. A ≥50% reduction in NRS score at 12 months was defined as pain response. Analysis of covariance and multivariable logistic regression were performed. Results: Ultrasonographic evidence of focal entrapment in at least one examined common peroneal or tibial nerve was identified in 42 patients (39.3%). Mean NRS scores decreased from 7.9 preoperatively to 2.7, 2.5, and 2.7 at 7 days, 6 months, and 12 months, respectively (all Holm-adjusted p < 0.001). After adjustment for baseline NRS score, the ultrasound-positive group had lower NRS scores at 7 days and 12 months than the ultrasound-negative group; the between-group difference was not statistically significant at 6 months. At 12 months, 77 patients (72.0%) achieved pain response: 35 of 42 ultrasound-positive patients (83.3%) and 42 of 65 ultrasound-negative patients (64.6%). Ultrasound-positive status was associated with higher odds of pain response after multivariable adjustment (adjusted odds ratio [OR], 3.69; 95% confidence interval [CI], 1.28–10.67; p = 0.016). Firth bias-reduced logistic regression yielded a similar estimate (OR, 3.32; 95% profile-likelihood CI, 1.26–9.81; p = 0.015). Conclusions: Preoperative ultrasonographic evidence of nerve entrapment was associated with more favorable postoperative pain outcomes after nerve decompression in patients with PDPN. Its potential prognostic value requires prospective validation.